The Long Valley Caledera and the Mono Inyo Craters

The Long Valley Caledra and the Mono Inyo Craters are located in an area in which volcanic eruptions have been occuring for over 3 million years. The caledra is an eliptical shaped area approximately 10 by 20 miles in size. The caledra was formed by a volcanic eruption 730,000 years ago, that resulted in the eruption of 150 cubic miles of volcanic ash and rock. Five miles below the surface of the caladera there is a partialy molten magma chamber.

Recent activity began in 1978 and interest grew, when in 1980, four magnatiude six earthquakes occured. The resultant activitiy has brought about an uplift in the central portion of the caledra.


USGS Long Valley Caldera Current Condition page

Forest-killing diffuse co2 emission at mammoth mountain is a sign of magmatic unrest

Earthquake activity in Long Valley Caldera and Vicinity, updated every half hour

Ground deformation detection

In the event of increased seismic activity the USGS will set up emergency field headquarters at the Long Valley Caldera. In the event of a declared watch a message is sent by USGS to California OES, which is responsible for notifying local authorities. If The USGS determines that there is a reason for issuing a warning about a potential eruption the USGS will notify the Governors of California and Nevada and others who will inform the public.

For more details about USGS's plan see the Long Valley Caldera Response Plan

Information on the Long Valley Caldera "Observatory"

Geologic History of Long Valley Caldera and Vicinity

FACT SHEETS on Long Valley caldera and the Inyo-Mono Craters volcanic complex

For more information about Volcanos see our Volcano Page

For information about earthquakes visit our Earthquake Center

For information for educators and school administrators visit our Schools Page

Visit our home page for links to other disaster subjects

Local Links

Information about Bishop

Mammoth Lakes

Newspaper Mammoth Times

Eastern Sierra College Center

Mammoth Lakes Foundation

White Mountain Research Station

Inyo National Forrest

Sking Mammoth Mountain

Bishop Internet Service Provider

This page is maintained by The Disaster Center. In the event of a Volcanic activity this page will be used to provide information about the event. If residents of the local area have any information which they would like to share with our site's visitors please send an E-mail to:

Penrose Conference Announcement

Application deadline was January 1, 2000.

Penrose Conference to address Longevity and Dynamics of Rhyolitic Magma Systems

A Geological Society of America Penrose Conference, "Longevity and Dynamics of Rhyolitic Magma Systems" will be held June 7-12, 2001, in Mammoth, California. Mammoth Mountain forms the southwest rim of the Long Valley caldera, one of three large Quaternary rhyolitic caldera centers in the United States. Long Valley, a site of recent volcanic unrest, lies at the heart of current debate over the mechanisms and time scales for the production, storage, and differentiation of rhyolite magma. Such information is critical to our understanding of fundamental geologic problems such as the formation and growth of Earth's continents and predicting volcanic hazards. The purpose of the conference is to bring together petrologists, geochemists, volcanologists and geophysicists actively studying the generation and evolution of silicic magmas. We hope to try and resolve, or at least constrain, a number of very important and currently highly topical issues pertaining to the shallow-crustal evolution of large, typically caldera-forming, silicic magma bodies. These include:

. What is a magma chamber-a large, long-lived fractionating liquid body or a "sleepy" crystal mush that gets kicked to life every so often, re-mobilizing existing material? A related issue is to what degree do plutons carry-forward, in some integrated way, the expression of this?

. What do crystals really represent-phenocrysts vs. xenocrysts-and what 'memory' do they retain? Related to this issue are questions such as does crystal growth- and dissolution-zoning reflect protracted fractionation of a single magma body or remobilization and dispersal of crystal mush during injection of fresh magma into the subvolcanic system and how do crystals move in the magma system - or are the crystals effectively static in a moving magma system?

. What is the efficacy of, and driving forces for, convection/mixing in silicic magmas? Can crystal disequilibrium features, such as chemical/isotopic zoning and dissolution surfaces, serve to discriminate between thermal convection and magma mixing?

. What are the time scales needed to produce large, rhyolitic magma bodies? Recent work using 40Ar/39Ar, Rb/Sr or U-series isotope data has led to the suggestion that rhyolite magmas in the Long Valley system are stored, following differentiation, for long (105-106) time scales. This contention has been disputed principally on the basis that it would be difficult to keep a body of magma thermally viable for such long periods, even if >500km3 volume. Alternative physical models have been proposed, such as remobilization of juvenile plutons or cumulate materials and ion microprobe work on zircons has variously upheld or contested the claims for long magma residence times. A key focus of the meeting will be to evaluate the different types of data available that bear on ages of magmatic events, and discuss their interpretations.

A limited number of keynote talks will serve to outline the current state of knowledge concerning the generation and evolution of large rhyolitic magma systems, and will set the foundation for evaluation of existing paradigms, development of new models, and discussion of future research directions. Most of the meeting will focus on poster sessions and group discussions. Mid-meeting field trips to selected Bishop Tuff and Sierran plutonic locations will serve to raise questions concerning limits and constraints on sampling and interpreting geochemical data from pyroclastic deposits based on our knowledge of how large silicic systems erupt, links between plutonic and volcanic environments, and the importance of recharge and mixing in magma evolution.

The conference is limited to approximately 50 participants to ensure a 'workshop-type' atmosphere focussed on manageable discussions. We encourage participation of graduate students working on silicic magma systems; partial student subsidies will be available. The registration fee, which will include lodging, some meals, field trips, and all other conference costs except personal incidentals, is not expected to exceed $750. Information on travel to the conference will be provided in the letter of invitation.

Co-conveners are: Kurt Knesel, Department of Earth Sciences, University of Queensland, St Lucia, Brisbane, Qld 4072, Australia,, ; George Bergantz, Department of Geological Sciences, Office Box 351310, University of Washington, Seattle, WA 98195-1310, USA,, ; Jon Davidson, Department of Earth and Space Sciences, UCLA, Los Angeles, CA 90095-1567,, Website: ________________________________________ Jon Davidson Professor of Geology and Geophysics Department of Earth and Space Sciences UCLA Los Angeles CA 90095-1567